The MIPI-DSI (mobile industry processor interface-display serial interface), which is defined and documented by the MIPI alliance, is a standard serial interface used for communications between a processor and a peripheral device (e.g. a display device) in a portable device. The MIPI-DSI interface has a feature of high speed communication with low power consumption.
The MIPI-DSI achieves data communications with one clock lane and one to four data lanes. Each lane includes two signal lines (a pair of signal lines) that transmit a differential signal. More specifically, the clock lane includes a pair of signal lines that transmit a differential clock signal and each data lane includes a pair of signal lines that transmit a differential data signal. The MIPI-DSI specification defines two communication modes: the LP (low power) mode and the HS (high speed) mode. The LP mode is a communication mode for communications at a low speed but with reduced power consumption, whereas the HS mode is a communication mode for communications at a high speed.
The MIPI-DSI interface is often used for communications between a host (e.g. a CPU (central processing unit)) and a display driver that drives a display panel, such as a liquid crystal display panel. A large amount of data including image data are exchanged between a display driver and a host, and the MIPI-DSI interface is especially suitable for this purpose. When the MIPI-DSI interface is used for communications between a display driver and a host, image data are usually transmitted in the HS mode, because it is necessary to transmit a considerable amount of image data in each horizontal sync period, which has a limited time duration. The use of the HS mode, however, undesirably increases the power consumption of the display driver.
It should be noted that Japanese Patent Application Publication No. 2012-150152 A discloses communications based on the MIPI-DSI specification in a liquid crystal display device.
Recently, the power consumption of a display driver tends to be increased due to advanced multifunctionality, while users desire reduction in the power consumption. To meet this requirement is important especially with respect to a display driver incorporated in a portable device. There is a technical need for reducing the power consumption of a display driver.